Whats a 1JYO part number from?

[xschop]

I googled to no avail....

[Jerry]

Yamaha uses the first 3 characters as an ID. So, if it is 1JY, closest I've found is a 4JY, a YZ 125F from the '90s. There is a 1JK from an SRX 600, 1J7 from a XS 750D. I also found a valve stem seal: 1JY-12119-00 YAMAHA VSYA-1JY .252x.410x.355.224.

Give us a clue; what are you looking at?

[xschop]

final drive

This is the number stamped on my FD hub....Its ugly but I can just barely read 1J7YO...I just googled it and it is from an xs750...I thought I had some rare xs1100 FD with the lower gear ratio....thanks Jerry....Well Folks the Secret is out....